1. POLYATOMIC IONS (must be memorized
POLYATOMIC IONS (must be memorized!) Polyatomic ions are mostly made of two non-metals.
Ions with -1 charge
chlorate ClO3-
nitrate NO3-
hydroxide OH-
acetate C2H3O2-
Permanganate MnO4-
Cyanide CN-
Ions with a -2 Charge
carbonate CO3-2
sulfate SO4-2
Ions with a -3 Charge
phosphate PO4-3
Ions with +1 charge
ammonium ion NH4+

2. Polyatomic Ions Rules
Changing the number of oxygens (in reference to the --ate) changes the name of the ion
perchlorate ClO4-1
chlorate ClO3-1
chlorite ClO2-1
hypochlorite ClO-1
Add 1 O  add per- prefix
--ate is the baseline
Subtract 1 O  change to –ite
Subtract 2 O  hypo--ite

3. More Rules to remember Adding a hydrogen to the ion changes
the name and the charge
carbonate CO3-2
bicarbonate HCO3-1
--ate is the baseline
Add 1 H  add bi- prefix & to charge

4. -1 These polyatomic ions match the charge of the single element
Ions with -1 charge
perchlorate ClO4-1
chlorate ClO3-1
chlorite ClO2-1
hypochlorite ClO-1